1. Field of the Invention
The present invention relates to a high-frequency signal line and an electronic device including the same, and more particularly to a high-frequency signal line preferably used for high-frequency signal transmission and an electronic device including the same.
2. Description of the Related Art
As a conventional high-frequency signal line, for example, a signal line disclosed in WO 2012/073591 is known. The high-frequency signal line includes a dielectric body, a signal line and two ground conductors. The dielectric body is a laminate of dielectric sheets. The signal line is located in the dielectric body. The two ground conductors are located in the dielectric body so as to sandwich the signal line in the direction of lamination. Accordingly, the signal line and the two ground conductors form a stripline structure.
One of the ground conductors has a plurality of openings at positions over the signal line when viewed from the direction of lamination. Thereby, little capacitance is created between the signal line and the ground conductor. Therefore, it is possible to reduce the distance in the direction of lamination between the signal line and the ground conductor having the openings, and it is possible to make the high-frequency signal line thinner. This high-frequency signal line is used, for example, to connect two circuit boards.
In order to facilitate the work for connection of two circuit boards via the high-frequency signal line disclosed in WO 2012/073591, the central portion of the high-frequency signal line in the lengthwise direction may be formed into a meandering shape. FIG. 31 illustrates a high-frequency signal line 500 of which a central portion in the lengthwise direction is meandering. FIG. 32 indicates a state where both ends of the high-frequency signal line 500 are pulled.
As seen in FIG. 31, the central portion of the high-frequency signal line 500 is meandering. Specifically, the high-frequency signal line 500 includes serially-connected line portions 502a through 502e. The line portion 502a extends in a right-left direction. The line portion 502b extends downward from the right end of the line portion 502a. The line portion 502c extends leftward from the lower end of the line portion 502b. The line portion 502d extends downward from the left end of the line portion 502c. The line portion 502e extends rightward from the lower end of the line portion 502d. The lengths of the line portions 502b and 502d are significantly shorter than the lengths of the line portions 502a, 502c and 502e. 
When the high-frequency signal line 500 is used to connect two circuit boards to each other, the left end of the line portion 502a is pulled leftward, and the right end of the line portion 502e is pulled rightward. In this state, as illustrated in FIG. 32, the high-frequency signal line 500 is deformed into a Z shape. Thereby, the distance between connectors provided on the both ends of the high-frequency signal line 500 is lengthened. Therefore, it is easy to connect the two connectors to the two circuit boards, respectively.
The high-frequency signal line 500, however, has a problem that via-hole conductors connecting the internally-provided two ground conductors may be damaged. More specifically, the high-frequency signal line 500 has a signal line and two ground conductors inside such that the signal line and the two ground conductors form a stripline structure, and the two ground conductors are connected to each other by via-hole conductors.
When the left end of the line portion 502a and the right-end of the line portion 502e are pulled leftward and rightward respectively, the line portions 502b and 502d are twisted. At this moment, a force is applied to the via-hole conductors provided in the line portions 502b and 502d, and the via-hole conductors may be damaged.